1. Field of the Invention
This invention relates to methods and systems for making painted vehicle panel skins and panels utilizing same and, in particular, to automated methods and systems for making painted vehicle body panel skins and panels, such as instrument panels, utilizing same.
2. Background Art
A vehicle body panel may include a rigid substrate panel, a layer of padding material, and a vinyl skin. When the panel is an instrument panel, the substrate material often times includes an opening which registers with an air bag. A door panel is hinged within the opening and the vinyl material bridges across the opening and the door panel. The prior art is known to promote tearing of the vinyl upon deployment of the air bag by molding the vinyl to provide a reduced cross section thickness of the vinyl skin at the desired location of the tear seam. It has also been proposed to score the vinyl skin using a laser or other cutting technique to weaken the skin and thereby provide a tear seam.
Referring to FIG. 1 (which corresponds to FIG. 1 of U.S. Pat. No. 6,348,172), a motor vehicle instrument panel cover 10 is shown for installation in a motor vehicle body to conceal and enclose such components as the instrument cluster, radio, and heating ventilating and air conditioning systems. The instrument panel cover 10 has a hidden air bag door 12, the edges of the door being generally located behind the indentation 14 in the surface or cover 10.
FIG. 2 (which corresponds to FIG. 2 of U.S. Pat. No. 6,348,172) shows the instrument panel cover 10 of FIG. 1 installed in the vehicle. The instrument panel cover 10 includes a rigid molded plastic substrate 18, a layer of urethane foam 20 and a vinyl skin 22. The instrument panel cover 10 is manufactured by placing the pre-molded substrate 18 and the pre-molded vinyl skin 22 in a mold and then injecting urethane foam into space between the substrate 18 and vinyl skin 22. Alternatively, the skin 22 may be placed on one half of the mold, the substrate 18 placed on the other half of the mold, and then the uncured foam poured into the mold before the mold is closed. Upon curing, the urethane foam 20 adheres to both the substrate 18 and the vinyl skin 22 and provides a layer of cushioning therebetween. As seen in FIG. 2 the instrument panel cover 10 encloses an air conditioning duct 24 and an air bag assembly 26. Air bag assembly 26 includes a conventional inflator 28 and a folded up air bag 30. The substrate 18 of the instrument panel cover has a generally rectangular opening 32 defined in part by a top wall 34 and a bottom wall 36. This opening 32 of the substrate 18 registers with the air bag assembly 26. An air bag door panel 40, of stamped steel or molded plastic construction has a top edge 42 which is suitably hinged to the substrate member 18 adjacent to the top wall 32 of the air bag opening 40 by suitable hinges which are not shown in the drawing. The bottom edge of the door panel seats on a flange 43 of the substrate 18. The layer of urethane foam 20 adheres the vinyl skin 22 to the hinged door panel 40.
Upon actuation of the air bag inflator 28, the air bag 30 is deployed against the backside of the door panel 40, causing the air bag door 40 to hinge upwardly and thereby permit deployment of the air bag into the occupant compartment of the vehicle. It will be understood and appreciated that the upward hinging of the door panel 40 will require tearing of the vinyl skin 22 along the path of the tear seam indentation 14 shown in FIG. 1.
Referring to FIG. 2, the lower edge of the hidden tear seam indentation 14 is provided at a shoulder 44 of the vinyl skin 22. Referring to FIG. 1, it is seen that the right hand portion of the hidden tear seam 14 is provided at a shoulder 46 and the left hand portion of the hidden tear seam 14 is provided at a shoulder 48 which melds into the cutout 50 for an air conditioning vent, not shown.
U.S. Pat. No. 6,348,172 discloses a method of making a thermoplastic skin including the steps of providing a mold having a mold surface with first and second mold surface portions which intersect at a sharp corner coincident with the desired location of the tear seam in the molded skin. The mold is oriented with one of the first and second mold surface portions oriented in a generally horizontally orientation and the other of the mold surface portions oriented in a generally vertical orientation. A thermoplastic material such as polyurethane is sprayed onto the mold surface and the curing of the sprayed material is controlled to permit gravity to induce flow of the sprayed material down the vertical surface of the mold at the sharp corner and thereby provide a cured skin which is of significantly lessened thickness at the corner than at other regions of the skin. Accordingly, the reduced thickness of thermoplastic material at the sharp corner defines the tear seam at which the skin material will tear upon deployment of an air bag against the skin.
As described in U.S. Pat. No. 6,877,972, solid urethane elastomer material may be used as part of a process for forming parts in a mold. The solid urethane elastomer is a two-part composition that is mixed at a spray head before applying the material to a mold. The urethane elastomer is formulated to set-up relatively quickly. For example, the urethane elastomer is sprayed from the spray head as a liquid and begins to set-up in about 10 to 15 seconds after it contacts the mold. In about two minutes, the urethane elastomer is cohesive and its surface is tack-free. Even with this relatively rapid set-up, when the urethane elastomer is sprayed on a vertical surface, the elastomer forms drips or runs on the vertical surface and may accumulate in liquid pools where a vertical surface meets a horizontal surface. It is also difficult to obtain a surface coating having relatively uniform thickness if the urethane elastomer is sprayed on a vertical surface because gravity causes the material to flow. On a horizontal surface, the urethane elastomer is easily applied to form a uniform thickness after it contacts the horizontal surface.
Examples of automotive parts that may include a urethane elastomer skin include instrument panels, inner door panels, consoles, glove box doors, steering wheel covers, body pillar covers, and the like. An example of a process for forming automotive parts having a urethane elastomer skin is provided below. In an in-mold painting process utilizing an aromatic urethane, the process would begin by applying paint to a mold release agent in the mold for the part. After painting, the aromatic or aliphatic urethane elastomer is sprayed onto the paint layer to form a wall having a thickness of approximately 1/16 to ⅛ inch. However, if the part has surfaces that are not substantially horizontal, but are vertical or sloped, the urethane elastomer will form drips and pools and have areas of reduced thickness. After the urethane elastomer has solidified, an injection molded part may be inserted into the mold on top of the urethane elastomer skin. The injection molded part provides reinforcement ribs, frames for installation of components such as air bags or instruments, and fastener receptacles. Foam is then injected into the mold to fill the mold and secure the injected molded part to the urethane elastomer skin. The part may then be removed from the mold and trimmed.
Recent developments in the manufacture of vehicles include incorporation of a plurality of air bags in the vehicle interior. Parts such as inner trim panels for doors, instrument panels and steering wheel covers that may be formed by the above-described process must be formed with more uniform wall thickness to meet part specifications for air bag covers.
U.S. Pat. No. 6,877,972 seeks to solve the problem of drips and pools of urethane elastomer by providing a mold which is moved by a mold manipulation tool to present differently oriented surfaces of the mold in a horizontal orientation when the urethane elastomer is sprayed on each of the differently oriented surfaces. A multi-axis robot is provided with a spray head that sprays the urethane elastomer onto a mold surface. A mold manipulator moves the mold that has a plurality of differently oriented mold surfaces so that the surface to be sprayed is held in a horizontal orientation as they are coated with the urethane elastomer and for a predetermined time period after spray coating until the urethane elastomer sets up.
Other related U.S. patent documents include U.S. Pat. Nos. 6,071,619; 6,902,758; 6,875,390; 6,991,841; 7,070,120; 7,121,578; 7,147,808; 7,147,809; 7,195,725; 7,273,572; 7,291,301; 2004/0061262; 2006/0091575; 2006/0006568; 2006/0008622; 2006/0029789; 2006/0261578 and 2007/0067994.
Despite all of the above-noted background art, there is still a need for a low cost, faster (i.e., greater throughput) yet simpler method and system for making vehicle body panel skins and body panels utilizing same while maintaining a soft and luxurious look and feel for the article.
Additional relevant art includes: U.S. Pat. Nos. 5,276,957; 6,428,718; 6,620,371; 6,686,007; 6,939,597 and 7,101,505; and U.S. published applications 2002/0041964; 2002/0158371; 2002/0171181 and 2006/0210662.